1. Field of the Invention
The present invention pertains to corrugated cardboard cartons and the like constructed from an integral blank to have internal flap members which are folded to provide a corner post support.
2. Brief Description of the Prior Art
Corrugated cardboard boxes are used today in many applications where relatively inexpensive lightweight containers, which may be shipped and stored in a compact configuration, are required. Different types of corrugated cardboard containers have been developed with either a unitary or a multiple component construction. Multiple components can, for example, be added to a corrugated cardboard container to improve its bursting or alternatively, its load-bearing strength. However, the use of multiple components for a container increases the material costs thereof, as well as labor costs, in providing the container to an end user. It is generally preferred that, if at all possible, a corrugated cardboard container is fabricated from a unitary blank which is folded into the desired container configuration. It is generally desirable that a corrugated cardboard blank have a design which is as efficient as possible, particularly for large production runs in which even small cost savings are magnified many times over.
Even in those applications where the strength of a corrugated cardboard container may be tested to its maximum limit, many users still prefer corrugated cardboard construction due to the cost savings thereof, as well as the ability of a carton manufacturer to at least partially preassemble the carton, thereby requiring the end user to supply only a modest amount of labor to complete the carton construction. Corrugated cardboard containers are also preferred because of their inherent lightweight and thermal insulation properties.
One particular application for corrugated cardboard containers which require, considerable container strength and which utilizes the insulation properties of the corrugated cardboard material is the meat packing industry, which uses corrugated cardboard containers to ship and store frozen meat products. Corrugated cardboard containers, for applications of this type, must exhibit substantial strength when one carton is stacked upon another, since even a carton of relatively small volume can hold frozen meat contents of considerable weight. When such cartons are stacked one on top of the other, the lowermost cartons need to bear the aggregate weight of the stack. Due to the relatively heavy weight of the frozen meat products, the loading applied to the lowermost carton can cause the carton to collapse, unless special measures are taken to prevent such collapse.
Unlike other products, such as reams of paper and the like, pressure on meat products disposed within the cardboard container must be avoided, because of their perishable nature. Accordingly, there is frequently provided a gap between the top of the carton contents and the top wall of the carton, with the top wall of the carton being supported internally, and when the weight of overlying carton is applied in compression to the side walls of the bottom carton. To provide a carton with greater strength so as to reliably withstand heavier loads stacked on top thereof, the carton can be made from thicker or heavier gauge cardboard material. However, there is a practical limit to the added strength and manufacturing economy of such carton constructions.
One option available to a carton designer is to provide additional, overlying walls to support or reinforce the outside, vertical walls of the carton. As mentioned above, it is generally preferable that such additional reinforcing walls, as with any component of carton, be obtained from a single unitary blank from which the carton is formed, so as to reduce assembly costs. One approach to improving the strength of corrugated cardboard cartons is to provide additional support only at the corners thereof, and not at mid-sections of vertical carton side walls, for example. For the reasons pointed out above, there is a demand for corrugated cardboard cartons having corner reinforcements of improved strength, especially such cartons formed from the unitary blank which need not have an increased size.